The increasing incidence of mosquito-borne diseases world-wide highlights the importance of mosquitoes to public health. Problems with mosquito resistance to insecticides, environmental concerns about insecticide use, parasite resistance to drugs, and slow progress in vaccine development indicate that new tools for vector management are badly needed. Development and application of control methods directed at the aquatic, larval stage of mosquitoes (e.g., toxic agents that are ingested by larvae) requires a thorough understanding of the feeding behavior, mechanisms, and food resources of larvae. The links between food and nutrient limitation in larval habitats and impact on larval growth, adult mosquito fitness and production emphasize the importance of larval feeding ecology to adult vectorial capacity. Given these relationships, the specific aims of this proposal are as follows: (1) to characterize the classes of nutrients and food resources available to mosquito larvae in natural habitats (marshes, tree holes, tires); (2) to examine experimentally the relationships between limiting nutrients, microbial biomass and diversity, and surface microlayer water fractions to mosquito growth and adult mosquito production for Aedes triseriatus, and Anopheles guadrimaculatus; (3) to examine the feeding mechanisms and changes in feeding behavior of larval Aedes and Anopheles in response to different food resources and physical factors associated with their natural habitats. The species and habitats we have chosen for study are broadly representative of mosquito-habitat relationships in other settings. Laboratory and field experiments include the following approaches: (1) Chemical and microbiological characterization of foods and nutrients in larval habitats, specifically proteins, essential fatty acids, carbohydrates, carbon and nitrogen, microbial biomass, and microbial diversity; (2) isolation and identification of bacteria (forming mosquito food) from habitats using selective and nonselective media, and modern identification methods based upon BIOLOG (carbon source utilization) and MIDI (fatty acid methyl ester) systems; (3) experimental manipulations of microbial biomass in habitats related to mosquito growth and adult production; (4) experimental supplementation of essential fatty acids and protein to measure mosquito growth responses; (5) importance of the surface microlayers to Anopheles growth; (6) food particle acceptance/rejection thresholds of Anopheles when particle type, size, flavor are varied; (7) microcinematographic and video analysis of hydrodynamics and feeding depth profiles of Anopheles, larvae; and (8) orientation of Aedes larvae to variably distributed food resources.